Plant Palette

Plant Palette

Asparagus

Photo of Jennifer Schultz Nelson

Jennifer Schultz Nelson
Extension Educator, Horticulture
jaschult@illinois.edu

We may be surrounded by flowers, but nothing says spring to me quite like the first taste of fresh asparagus. I've always wanted to try growing my own, and now that I have my own home I finally get my chance! In talking to fellow gardeners about growing asparagus, they seem to fall into two camps: those who failed at growing asparagus and say it's too much work to try again, and those successful at growing asparagus and love the work that goes into it. We'll see where I fall, but I am very stubborn, so maybe that character trait will work in my favor where asparagus is concerned.

Asparagus is a pretty unique vegetable. For one, it's a perennial, which is unusual for a vegetable. Also, it grows wild along roadsides and railroad tracks across much of the United States. Asparagus is native to Asia Minor, which roughly corresponds to modern-day Turkey. Given its close proximity, it is not surprising that historically, the Greeks were the first to cultivate asparagus over 2500 years ago.

The name asparagus comes from the Greek word for "sprout" or "shoot". The Greeks used it as a medicinal herb, believing it had powerful cleansing and healing properties. The Romans quickly became lovers of asparagus as well. In their conquests of the known world, they also spread their fondness for asparagus far and wide.

Asparagus became incredibly popular with Europeans in the 16th century, particularly in France and England. King Louis the XIV of France loved it so much, he ordered greenhouses built solely for growing asparagus! As Europeans began to colonize the New World, they brought with them their prized asparagus plants.

Botanically, asparagus is in the lily family, as are onions, leeks, and garlic. In asparagus, the stem functions as a leaf would, by photosynthesizing. The leaves have been reduced to flattened scales located at the top of the spear. The plants are also dioecious, meaning there are separate male and female plants. The female plants typically yield less and have thinner spears because they channel energy into producing seed. All male cultivars are available which produce relatively greater numbers of thicker spears.

Growing asparagus is best reserved for patient people, as a crop cannot be harvested for three years after planting. This frustrates many home gardeners, and is one factor that makes asparagus more expensive in stores, since commercial growers must spend time and money to weed and maintain plots before they yield any asparagus.

Asparagus does start as a seed. The first year, the plant primarily develops a crown, or growing point with an extensive root system. The second year, the crown begins to produce a fern-like portion above ground. It isn't until the third year that the characteristic asparagus spears emerge from the crown in the spring and early summer. A well-maintained bed will keep producing each year for 20 years or more.

In major production regions like California, differences in micro-climates allow production from January through May. Farm workers walk fields daily and harvest asparagus by hand, which also factors into its higher price in stores. Michigan and Washington also produce asparagus, but far less than California.

When growing asparagus at home, look for all male hybrids such as Jersey Knight, Jersey King, and Jersey Giant. These were developed in New Jersey, the 4th largest producer of fresh asparagus. Not only do these all male hybrids yield more, they show resistance to rust and fusarium, common fungal diseases in asparagus.

Asparagus grows best in well-drained, even sandy, soil. Weed control is crucial to developing a good crop. Many myths circulate about applying table salt to asparagus plantings to control weeds. Although it is true that asparagus will tolerate higher salt levels in soil than most weeds, this is a poor weed management strategy. The excess salts inhibit water penetration into the soil, potentially stressing the asparagus plants. It is also very likely that excess salts will leach out of your asparagus bed and affect other plants.

Plant asparagus at the edge of the garden so they are not disturbed when tilling the garden in the spring. A western exposure is the best place for asparagus, so that the tall ferns that develop after the spears do not shade the rest of the vegetable plants. Leave the fern-like growth intact until it turns brown in the fall. Like spring bulbs, the foliage of asparagus helps generate energy for the following year. Asparagus beetles are a common insect pest on the foliage, and can be controlled per label directions with an insecticide specifically labeled for these beetles.

Plants should be fertilized each spring before shoots emerge with 20 to 25 pounds per 1,000 square feet of a balanced fertilizer, followed by another dose after the last harvest. Maintain quality in your harvest by never harvesting every shoot. Let a portion develop ferns to fuel next year's harvest.

You may have seen white asparagus for sale, and wonder "How'd they do that?" White asparagus is regular green asparagus that has had soil loosely mounded over the top as shoots emerge. The shoots remain milky white without exposure to sunlight. Of course it's a lot more labor intensive than regular asparagus, so it's more expensive in the store.

Remember the Master Gardener Plant Sale is Saturday, May 6th from 9 a.m. to noon at the U of I Extension Office at 2535 Millikin Parkway, Decatur. There will be over 300 daylilies and hosta, plus other perennials and some annuals. Most prices range from $1 to $5. I will offer a "build your own container" workshop throughout the morning where $15 gets you a 12 inch pot, soil, and your choice of annual plants to combine for your very own horticultural masterpiece. See you there!

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